This invention relates to certain herbicidal sulfonamides, agriculturally suitable compositions thereof and a method for their use as a selective Preemergent or postemergent herbicide or as a plant growth regulant, particularly for the control of undesired vegetation in rice.
New compounds effective for controlling the growth of undesired vegetation are in constant demand. In the most common situation, such compounds are sought to selectively control the growth of weeds in useful crops such as cotton, rice, corn, wheat and soybeans, to name a few. Unchecked weed growth in such crops can cause significant losses, reducing profit to the farmer and increasing costs to the consumer. In other situations, herbicides are desired which will control all plant growth. Examples of areas in which complete control of all vegetation is desired are areas around railroad tracks, and industrial storage areas. There are many products commercially available for these purposes, but the search continues for products which are more effective, less costly and environmentally safe.
The "sulfonylurea" herbicides are an extremely potent class of herbicides discovered within the last few years which generally consist of a sulfonylurea bridge, --SO.sub.2 NHCONH--, linking two aromatic or heteroaromatic rings.
U.S. Pat. No. 4,801,327 and EP-A-209,230 disclose, in part, herbicidal sulfonamides of the formula ##STR1## wherein X.sub.a is CH.sub.2, CH(CH.sub.3), CH.sub.2 CH.sub.2, CH.sub.2 CH.sub.2 CH.sub.2 or CO;
E is a single bond, CH.sub.2 or O; PA1 Q is, inter alia, a 5-membered heterocyclic ring, containing 2-4 atoms of carbon and 1-3 heteroatoms selected from the group consisting of 0-2 oxygen, wherein sulfur may take the form of S, SO or SO.sub.2, and containing one or two carbonyl or sulfonyl (SO.sub.2) groups, etc.; and PA1 R.sub.1 is H, C.sub.1 -C.sub.3 alkyl, C.sub.1 -C.sub.3 haloalkyl, halogen, nitro, C.sub.1 -C.sub.3 alkoxy, SO.sub.2 NR.sub.a R.sub.b, C.sub.1 -C.sub.3 alkylthio, C.sub.1 -C.sub.3 alkylsulfinyl, C.sub.1 -C.sub.3 alkylsulfonyl, CH.sub.2 CN, CN, CO.sub.2 R.sub.c, C.sub.1 -C.sub.3 haloalkyl, C.sub.1 -C.sub.3 haloalkylthio, C.sub.2 -C.sub.4 alkoxyalkyl, C.sub.2 -C.sub.4 alkylthioalkyl, CH.sub.2 N.sub.3 or NR.sub.d R.sub.e. PA1 n is 1 or 2; and PA1 Q is, inter alia, a fully unsaturated 5- or 6-membered ring containing 1 to 3 heteroatoms selected from 0-1 S, 0-1O or 0-3 N, etc. PA1 1. Compounds of Formula I wherein PA1 2. Compounds of Preferred 1 wherein R is Cl. PA1 3. Compounds of Preferred 2 wherein X is CH.sub.3 or OCH.sub.3.
EP-A-164,268 disclose, in part, herbicidal sulfonylureas of the formula ##STR2## wherein
R.sub.1 is H, F, Cl, Br, CH.sub.3, CF3, OCH.sub.3, SCH.sub.3, OCHF.sub.2 or SCHF.sub.2 ;
The compounds of the instant invention are within the generic disclosure of the above references but the compounds of the instant invention are not named and their particular utility for control of undesired vegetation in rice is not disclosed.